Scanning photoelectron microscopic study of top-emission organic light-emitting device degradation under high-bias voltage

The degradation process of a top-emission organic light-emitting device (TOLED) under high-bias voltage was investigated using a scanning photoelectron microscope (SPEM). The TOLED was in situ biased to reveal the degraded area inside the SPEM chamber. The SPEM data showed a volcano-type structure inside the degraded area. The overall results of the spectroscopic analysis suggest that strong degradation was accompanied by an eruption underneath the cathode layer. It is posited that the hot gases from the erupted area separated the cathode layer from the organic layer, forming a large bubble, and that, as the bubble exploded, the pressure of the gas blew away the cathode layer. (c) 2006 American Institute of Physics.